This disclosure is related generally to the field of rope terminations. The disclosure may have applications in the field of mechanical sheaves. The disclosure may have benefit when applied to marine surveying operations.
In geophysical prospecting in a marine environment, cable configurations are often towed behind a vessel to deploy equipment such as energy sources and sensor cables. Such cables frequently use ropes connected to structures on the vessel that provide load bearing and freedom of movement for the cables. Traditional connections include sheave-to-bolted connections and thimble to shackle connections. The connector, sheave or thimble, may be constrained to move substantially in a plane perpendicular to an axial centerline of the connector in some cases. When a rope termination is constrained by such connector to one degree of freedom or less, a rope tension direction that does not lie in the plane perpendicular to the centerline of the connector may introduce a fleet angle, defined as the angle between the centerline of the connector, for example a sheave, and the rope axis at the edge of the connector. A fleet angle may be created by any number of circumstances, including, for example, misalignment of two sheaves, misalignment of a sheave and a bad, vibration or strumming of the rope, or by winding the rope around a drum. The fleet angle may result in increased stress and friction wear on the rope at the edge of the connector.
Excess wear on ropes results in the need to replace and repair ropes, causing idle time in the geophysical prospecting industry to repair connections for energy sources and sensor cables, for example. There is a need in the industry for rope terminations that reduce wear.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation.